Parent, Child

GGB doesn't encapsulate objects or parent them. This worksheet is a picture of parenting.
To trick GGBScript into doing it, I use the fact that vectors update improperly. Consider vector d. I move point Q, and its script executes. d has not yet updated. So d holds its previous value. I can use this to perform translation:
The update script of Q reads:
SetValue[D, Q + d]
SetValue[E, Q + e]
SetValue[F, Q + f]
This must be done one point at a time. Construction order matters, and DynamicCoordinates are more difficult to handle.
Alternately, to get similar behavior, we can draw the rectangle with base QR, and use PointIn[] for vertices D,E,F, but ΔDEF will no longer respond to mouse-over-and-drag.